HGF and bacterial pneumonia: - Growth factor delivery: EVs deliver reparative factors like HGF and KGF to injured lungs. EV-derived HGF was essential for anti-fibrotic effects in ARDS-fibrosis, and KGF in MSC-EVs partly mediated improved survival in bacterial pneumonia (20, 30) - Inhibition of pro-fibrotic pathways: MSC-EVs interfered with TGF-β/Wnt/β-catenin signaling and epithelial–mesenchymal transition. Treated ARDS mice had lower β-catenin activation and maintained epithelial markers (E-cadherin) vs. controls (53)